No..no...the engine is not just weak when the A/C is switched on....nearly all 4 cyl. motors act that way...my sportage literally stops and will not move! This problem just recently cropped up....it didn't do this before. But turn the A/C off; accelerate, then once you're going, turn it back on, and everything runs like normal, until you get to the next stop sign. I will take some voltage measurements to verify, and when the fan clutch dies again, i'll probably do the electric fan install! And yes, Axe Man, it has codes...it's had codes for 2 years now, continuously, i've had it at 3 different Kia dealers and 2 independent shops in the dallas area, and spent almost five thousand dollars dollars on it, and nobody could ever make the codes stop coming. I'm still fighting with one dealer and Kia of America about that. Literally everything was changed..every sensor, including the computer and all the electrical wiring harnesses for the engine. The only thing that hasn't been replaced is the crankshaft sensor. Kia just scratches their head and asks for more money. :P Only someone who REALLY loves his Kia would try so hard to fix it!